Using an XSL stylesheet together with an ASP.NET XML control can be a great way to format the output of a database query. For instance a cool implementation is that you can embed an XML control within a ListView control so that you can output a tree-like structure in your ListView rather than the standard tabular structure.
So How Can One Set Up An XSL Variable?
Thankfully it’s actually quite straightforward to set up and use an XSL variable. The only real difference is the way that its done. Rather than the syntax of traditional languages where you would declare and populate the variable (ie: var myVariable = ‘some data’), you actually create an Element with an attribute set to the value that you want to set.
So, for example, to set up a variable in XSL that is populated with data from a database query, you could write this as:
<xsl:variable name="myVariable" select="SomeData"/>
Below is a slightly more complete example with a few more lines of code added in order to give you a better idea:
<xsl:template match="MyRoot/UserData"> <xsl:if test="SomeData"> <xsl:variable name="myVariable" select="SomeData"/>
From the example code above, within your template match you first test to see if the database value ‘SomeData’ has been returned as a data-populated XML node. If this is indeed the case, then you can declare and populate your new variable named myVariable.
As you can see, the XSL tag xsl:variable sets up the markup as a variable type element. You use the name= attribute to declare the name that you want to use for your variable. Then you use the select= attribute to state the text from which node that XSL should use to populate your variable.
Naturally if you want to use the text from an attribute rather than from a node you can use the @ symbol in front of your attribute name (along the lines of select=”@SomeData”).
So from the code above, you can see that much of the logic involves testing the XML structure to make sure the element is valid. The two main components are:
- Setting up your variable element to get the necessary information from your XML file/feed.